Agricultural harvesters are configured to receive cut crop from harvesting devices mounted at the front of the agricultural harvester, to thresh, separate, and clean that crop and to store that crop in a reservoir on the agricultural harvester commonly called a grain tank or grain bin. The grain tank or grain bin is typically an open topped structure disposed at the very top of the agricultural harvester.
When the grain tank is full, the operator must stop the agricultural harvester and wait until it can be unloaded. It is generally preferred not to stop the agricultural harvester for the unloading process, but to permit the harvester to cut and process crop continuously, unloading the harvester to a secondary vehicle, often called a grain cart (typically pulled by an agricultural tractor) or grain truck as the agricultural harvester moves through the field with the grain cart or truck alongside.
To ensure that unloading happens at the appropriate time, the operator of the harvester must regularly and periodically check the level of grain in the grain tank. For prior art agricultural harvesters, this requires that the operator stop watching the field he is harvesting, turn his head, crane his neck, and look through a small window at the top of the grain tank, to see whether the crop has reached an almost-full level. The operator will see nothing in the small window until the grain bin reaches perhaps 95% full.
This last-minute visualization means that the farmer may have to stop harvesting, send a radio communication and wait for the grain truck to arrive. This is a very inefficient use of the combine, since any time spent waiting and not harvesting is wasted time.
To give the operator a better estimate of the level of grain in the grain tank and to permit him to keep looking forward at the field he is harvesting, some manufacturers provided grain tank level sensors fixed to the wall of the grain tank. These sensors signal a circuit (when actuated) to indicate the corresponding fill level of the grain tank. The switches may be located to actuate at different fill levels, such as 75% and 100% of full. 100% of full meaning in this context that the grain tank is filled to its recommended carrying capacity.
In these arrangements, a visual or audible signal is provided to the operator in the operator cabin indicating the level of grain in the grain tank. Visual signals are presented in front of the operator so the operator can determine the level of grain without having to turn his head. Unfortunately, these arrangements indicate only a few levels to the operator, each level corresponding to a different level switch in the grain tank.
More recently, new arrangements have been invented that indicate the grain level in the grain tank with a higher resolution. For example, one design includes an ultrasonic sensor disposed above the grain tank that shines downward on the top of the grain. The ultrasonic sensor is capable of determining the height of grain in the grain tank to within a few cm. See, for example, U.S. patent application Ser. No. 11/402,782, which is assigned to Deere & Co. the assignee of the present application.
In another arrangement, the grain level in the grain tank is calculated by integrating an inlet grain flow rate of the grain coming into the grain tank and an outlet grain flow rate of the grain leaving the grain tank via an unloading conveyor. See, for example, U.S. patent application Ser. No. 12/164,926, which is assigned to Deere & Co., the assignee of the present application.
In both these applications, the operator is provided with the fill level of the grain tank. Since these arrangements have been developed, a new concern has arisen. The operator may not want the actual level in the tank indicated. Instead, the operator may wish to have the display indicate an arbitrary level or volume of grain in the grain tank different from the actual level or volume. For example, the operator may wish to contact the grain truck driver when the grain tank is 85% full to signal him to return for further unloading. Alternatively, the operator may want the display to indicate “full” when the grain tank is only 60% full in order to avoid getting stuck in soft ground. In both of these cases the operator has preference for displaying the grain tank as “full” at a level that he deems full under the conditions, which may be less than the absolute volumetric capacity of the grain tank.
To date, no system known to the inventors provides the operator with an easy way to change the scale values of the display in the operator cab. While the means described above permit the accurate measurement of the level of grain, they do not permit the operator to scale the display according to arbitrary grain tank fill levels that he deems most useful. It is an object of this invention to provide such a system.